I've actually took dental assisting course in high school, and it was one of the electives in my school 🙂 I started working as a dental assistant in senior of my high school building up a lot of experiences, came to college and worked around my schedule. Long story short, if you have a lot of experience and you know what you are doing, try to get a part time job and maybe work two days or one day a week. If you don't have experience, go in as a internship maybe 2-3 hours a week, and maybe they will ultimately hire you.
I work part time in a dental office, and when I'm in school, I work one day a week, literally on Friday from 12-6. It's a small office, but the one day I go in, I verify insurance for the whole week, calculate $$, coordinate schedule etc... More experience you have, the more doctors will appreciate you and be willing to work around your schedule. And let them know you really want to be a dentist, so open your ways up!!